The Arlington County Board will hold a public hearing May 31 on a request by the Arlington Telecommunications Corp. (ARTEC) that its rates be deregulated. At the meeting, the board also is expected to decide whether to grant ARTEC, the area's first major cable television venture, a rate increase in lieu of deregulation.

Last week ARTEC, which began service nearly two years ago, urged the board to deregulate its rates because, in the words of company officials, "The Arlington marketplace is the most efficient price regulator."

"Regulation of a nonessential industry is an affront to the free enterprise economic system on which this country has been built," franchise president Thomas W. Richards, a former County Board chairman, said in a letter urging deregulation.

ARTEC officials have said that regulation in unnecessary, because there are alternatives to cable service. For example, company officials suggest, viewers who now tune in to House of Representatives hearings can instead go to the House and watch the hearings. Those who want stock quotations and financial news can get the same information from newspapers.

ARTEC has not been granted a rate increase since 1975, officials said, although the monthly price of Home Box Office, which features movies, was raised $1 in January to $9.95. Cable installation currently cost $25 with a monthly service charge of $7.95.

Richards told the County Board ARTEC would favor a $2 monthly increase in the service charge. "Whatever the increase is, you get 4 percent," he said, noting that the county receives a 4 percent business tax on ARTEC's profits. This year ARTEC is expected to pay about $151,000 on gross revenues of $3.7 million. "Ours is really a symbiotic relationship."